Radiation therapy system

ABSTRACT

A radiation therapy system comprises a beam delivery system located in a treatment room. The beam delivery system comprises a particle accelerator for generating a radiation beam, and a positioning apparatus for moving the particle accelerator to any one of a plurality of treatment locations in said treatment room. The system includes a plurality of waiting rooms each having a patient support apparatus that is movable between a waiting state in which it is located in the respective waiting room, and a treatment state in which it is located in a respective one of the treatment locations in the treatment room. The positioning apparatus comprises a counterbalanced lever which carries the particle accelerator. The particle accelerator is preferably a proton accelerator producing a proton beam.

CROSS REFERENCE TO RELATED APPLICATION

The present applications claims the priority benefits of InternationalPatent Application No. PCT/EP2018/078772, filed Oct. 19, 2018, andclaims benefit of Great Britain Patent Application No. 1717238.8, filedOct. 20, 2017.

FIELD OF THE INVENTION

The present invention relates to radiation therapy systems. Theinvention relates particularly, but not exclusively, to proton beamtherapy systems.

BACKGROUND TO THE INVENTION

The NHS (National Health Service) in the United Kingdom and CRUK (CancerResearch UK) published a vision for future innovation in Radiotherapy2014-2024 calling for improvements in cost, effectiveness, accessibilityand technology for tumour-specific radiotherapy (RT).

Presently, RT is used to treat 40% of cancer patients, but currentprovision is hampered by lack of tumour specificity and toxicity, andthe lack of a combined imagining modality that ensures tumours areproperly targeted. Conventional X-rays are the current gold standardmodality, but have inherent limitations in dose distribution. X-raysfrom medical linear accelerators (linacs) are the most commonradiotherapy modality and are used in the treatment of 50% of cases.Although linac-based RT is cost-effective, it has disadvantages,including radiation-induced morbidity and carcinogenesis, which arelargely caused by high entrance and distal doses in normal tissues. Aslinacs need to be replaced/upgraded every 10-20 years, they present alarge financial burden to healthcare. Because X-ray radiotherapy is onlypartially effective and has side-effects, a key healthcare challenge isto find a more effective, less toxic and widely available modality sothat patients receive appropriate and optimal care promptly, whilemeeting the increasing demand for radiotherapy.

Treatments using other charged particles, such as protons and ions, isknown but are currently prohibitively expensive. The main cost driversof proton and ion beam therapy are the proton and ion accelerators andbeam delivery systems, which typically require very large gantries. Thegantries themselves require high-tech engineering, with low productionvolume and are therefore expensive. The placement of the treatmentrooms, which tend to be spread out over a large area also increases theoverall cost. Single treatment room systems where the proton acceleratoris placed on a gantry have also been proposed, but these are largesystems requiring gantries and are relatively expensive because of theprovision for only one treatment room. The foot print of the building isalso influenced by the length of the beam line feeding the varioustreatment rooms and the required shielding along the beam line. Inaddition, with convention treatment systems it is difficult to makeefficient use of the radiation equipment given the relatively long timesrequired to set up the equipment for each patient and for organising thepatients themselves.

Nevertheless it is understood that for the purpose of therapy, protonsprovide a superior form of radiation compared to photons. For example,radiotherapy modalities such as proton and ion beam therapies are moreeffective because of their favourable dose distributions, where the“spread-out Bragg peak” can be made to conform to tumour shape withnegligible distal dose, and there is a reduction in carcinogenesisarising from the treatment. Unfortunately the benefits of proton therapyhave been overshadowed by the relatively high cost of conventionalhospital based facilities.

By reducing the treatment cost of proton therapy the number of cancerpatients receiving radiotherapy would increase. Making radiotherapytechnology more affordable and widespread would improve the health andquality of life of cancer patients. The economy would also benefitthrough cost savings.

SUMMARY OF THE INVENTION

A first aspect of the invention provides a radiation therapy systemcomprising:

-   -   a beam delivery system located in a treatment room, the beam        delivery system comprising        -   a particle accelerator for generating a radiation beam, and        -   a positioning apparatus for moving said particle accelerator            to any one of a plurality of treatment locations in said            treatment room;    -   a plurality of waiting rooms;    -   a respective doorway between each waiting room and said        treatment room;    -   a respective patient support apparatus for each waiting room;        and    -   a respective actuation apparatus for moving each patient support        apparatus between a waiting state in which it is located in the        respective waiting room, and a treatment state in which it is        located in a respective one of said treatment locations in said        treatment room.

In preferred embodiments said positioning apparatus comprises acounterbalanced lever carrying the particle accelerator. Said lever maybe pivotable at a fulcrum about a horizontal axis, said fulcrumpreferably being located at the centre of said treatment room. Typicallysaid particle accelerator is located on one side of said fulcrum and acounterbalancing unit is provided on the other side of the fulcrum.

In preferred embodiments, said positioning apparatus is rotatable abouta vertical axis to move said particle accelerator to any one of saidtreatment locations, said vertical axis preferably being located at thecentre of said treatment room.

Advantageously said fulcrum is coincident with said vertical axis.

Preferably the particle accelerator is coupled to the positioningapparatus for rotational movement about at least one axis, or two orthree orthogonal axes, with respect to the positioning apparatus.

Advantageously said particle accelerator is provided with a beam outputdevice, preferably comprising a beam delivery nozzle.

In preferred embodiments each of said treatment locations is arespective part of said treatment room associated with a respective oneof said waiting rooms.

Typically each of said treatment locations is a respective part of saidtreatment room that is adjacent the door of a respective one of saidwaiting rooms.

In preferred embodiments at least some of, and preferably all of, saidwaiting rooms are radially spaced apart around said treatment room.

Preferably, said waiting rooms are arranged in a ring around saidtreatment room.

Preferably, said actuation apparatus is configured to move therespective patient support apparatus in a main axial direction into andout of the treatment room, said main axial direction preferably beingradially disposed with respect to said treatment room. Optionally saidactuation apparatus is configured to move the respective patient supportapparatus along two or three orthogonal axes.

Optionally said actuation apparatus is configured to effect rotationalmovement of the patient support apparatus about at least one axis, andoptionally about two or three orthogonal axes.

Conveniently said actuation apparatus comprises an articulated arm. Thearticulated arm may be coupled between a base and said patient supportapparatus. The base is preferably located in the respective waitingroom.

Preferably said actuation apparatus and/or said positioning apparatusare power operated.

In preferred embodiments the system includes a control system forcontrolling said beam delivery system for delivering a radiation beam toa target zone in accordance with a three dimensional beam deliveryvector.

Preferably said control system is configured to control said beamdelivery system by operating said positioning apparatus to position saidparticle accelerator for delivering said radiation beam to said targetzone in accordance with said three dimensional beam delivery vector.

In preferred embodiments said control system is configured to controlany one or more of: the rotational position of the positioning apparatusabout a vertical axis; the height of the particle accelerator; therotational position of the particle accelerator about one or more axis.

In preferred embodiments the system includes means for detectingmovement of a patient on the patient support apparatus, the system beingresponsive to detected patient movement to adjust the position of saidparticle accelerator.

The control system may be responsive to detected patient movement toadjust said beam delivery system for maintaining delivery of saidradiation beam to said target zone in accordance with said threedimensional beam delivery vector.

The system may include means for detecting movement of a patient on thepatient support apparatus, the system being responsive to detectedpatient movement of more than a threshold amount to stop delivery ofsaid radiation beam.

A second aspect of the invention provides a beam delivery system for aradiotherapy system, the beam delivery system comprising a particleaccelerator for generating a radiation beam and a positioning apparatusfor moving said particle accelerator, wherein said positioning apparatuscomprises a counterbalanced lever carrying the particle accelerator. Itwill be understood that any one or more of the aforementioned featuresof the beam delivery system, particle accelerator and positioningapparatus may be provided with the beam delivery system of the secondaspect of the invention.

Further advantageous aspects of the invention will be apparent to thoseordinarily skilled in the art upon review of the following descriptionof a specific embodiment and with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is now described with reference to theaccompanying drawings in which:

FIG. 1 is a perspective view of a radiation therapy system embodying oneaspect of the present invention, the system being shown in a cut-awaymanner;

FIG. 2 is a plan view of the system of FIG. 1;

FIG. 3 is a perspective view of a patient being treated by the system ofFIG. 1;

FIG. 4 is an alternative view of the patient being treated by thesystem; and

FIG. 5 is a further alternative view of the patient being treated by thesystem.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now in particular to FIGS. 1 and 2 of the drawings there isshown, generally indicated as 10, a radiation therapy system embodyingone aspect of the present invention. The system 10 includes a radiationbeam delivery system 12 and a plurality of waiting rooms 14, theradiation beam delivery system 12 being operable to deliver a radiationbeam to a patient 26 from any one of the rooms 14 at a time. In typicalembodiments there is a single beam delivery system 12 servicing all ofthe rooms 14.

The beam delivery system 12 comprises a particle accelerator 16 carriedby a positioning apparatus 18. The particle accelerator 16 may compriseany suitable conventional particle accelerator, for example a linearaccelerator, a cyclotron, a synchro-cyclotron, a synchrotron, or a laserbased accelerator, and produces a radiation beam (not illustrated) foruse in patient treatments, in particular tumour RT. The radiation beamtypically comprises ionizing radiation. The nature of the radiation beamdepends on the radiation source (not shown) with which the particleaccelerator 16 is used. In preferred embodiments, the radiation sourcecomprises a source of protons. As such the radiation beam comprises aproton beam and the system 10 may be described as a proton therapysystem. Alternatively, the radiation source may comprise other suitableparticles, especially but not exclusively charged particles, for exampleions (e.g. Carbon ions, Helium ions or Neon ions), atoms, photons orother sub-atomic particles such as electrons, alpha particles, betaparticles, negative pi mesons or neutrons. Hence, in alternativeembodiments the radiation beam may comprise, for example, an ion beam,electron beam (especially a relativistic electron beam), a neutron beamor X-ray beam. The radiation source may be incorporated into theparticle accelerator 16 or connected to it in any convenientconventional manner.

The particle accelerator 16 has an output device, typically comprising anozzle 24, for delivering the radiation beam to the radiation target,i.e. the patient 26 from the relevant waiting room 14. The nozzle 24 maybe configured to bend, scan, focus or otherwise manipulate the radiationbeam at the point of delivery, and to this end may include one or morebending, scanning and/or focusing magnets (and/or other beam formingand/or beam manipulating and/or energy selection components as required)for energy selection, bending, scanning and/or focusing the radiationbeam at the point of delivery as required. Optionally, the nozzle 24 maybe extendible in its longitudinal direction. The nozzle 24 may beconventional. Typically, the nozzle 24 is fixed with respect to theparticle accelerator 16 so that it moves with the particle accelerator16. In preferred embodiments there is no beam transport system betweenthe particle accelerator 16 and the nozzle 24, in particular no beamtransport system that bends the radiation beam between the particleaccelerator 16 and the nozzle 24. This simplifies the beam deliverysystem 12, reducing cost and increasing reliability. It will be seenthat in preferred embodiments, positioning the particle beam withrespect to a patient involves moving the whole accelerator 16, andtherefore the nozzle 24, by means of the positioning apparatus 18.

In preferred embodiments the beam delivery system 12 is located in atreatment room 15 that is adjacent each of the waiting rooms 14.Conveniently the waiting rooms 14 are radially spaced apart around thetreatment room 15. In preferred embodiments, the rooms 14 are preferablyarranged in a ring around the treatment room 15. The treatment room 15may therefore be circular. Twelve waiting rooms 14 are shown in theillustrated example although in alternative embodiments there may bemore or fewer waiting rooms. Although it is preferred that the waitingrooms 14 encircle the treatment room 15, this is not essential. Inalternative embodiments, the waiting rooms 14 may be arranged in one ormore arc formation located adjacent the treatment room 15 (in which casethey may still be radially spaced apart), or may be arranged in one ormore linear formation, i.e. in one or more row, located adjacent thetreatment room 15. In such cases the waiting rooms 14 may only partiallysurround the treatment room 15. In cases where the waiting rooms 14 doform a ring surrounding the treatment room 15, the ring may be circular(as illustrated) or any other suitable shape, e.g. rectangular orpolygonal. In the illustrated embodiment, the waiting rooms 14 areprovided in a single tier. In alternative embodiments the waiting rooms14 may be provided in more than one tier. Each tier may have the samearrangement of waiting rooms or a different arrangement of waiting roomsas is required.

A respective doorway 17 is provided between each waiting room 14 and thetreatment room 15, each doorway 17 having a respective door 19. In theillustrated embodiment, each door 19 is a sliding door, comprising firstand second slidable door leafs 19A, 19B. Alternatively, each door maycomprises a single leaf, or more than two leafs, and may open and closein any convenient manner, e.g. slidably or hinged. Preferably, the doors19 are configured to provide radiation shielding to the occupants of therespective room 14, e.g. the respective patient 26 and any medical staffthat may be present. This may be achieved in any conventional manner,including selection of the material from which the structures are madeand/or their thickness, and/or by providing appropriate cladding (notshown).

The walls 42, and optionally the floor and ceiling, of the rooms 14, 15may be configured to provide radiation shielding to the room occupants.This may be achieved in any conventional manner, including selection ofthe material from which the structures are made and/or their thickness,and/or by providing appropriate cladding (not shown).

The treatment room 15 has a wall 47 that provides a barrier between thewaiting rooms 14 and the treatment room 15. The doorways 17 are formedin the wall 47 and the respective doors 19, when closed, serve as partof the barrier.

Each waiting room 14 is associated with at least one patient supportapparatus 38, typically in the form of a chair, couch, platform or bed,for accommodating the patent 26 during use. The support apparatus 38provides at least one of, and may be operable between any two or more ofthe following configurations: a standing configuration (in which itsupports the patent in a standing position), a sitting configuration (inwhich it supports the patient in a sitting position), a fully reclinedconfiguration (in which it supports the patient in a fully reclinedposition), and one or more semi-reclined configurations.

Each patient support apparatus 38 is supported by an actuation apparatus40 configured to move the patient support apparatus 38 between a waitingstate, in which the patient support apparatus 38 is located in therespective waiting room 14, and a treatment state, in which the patientsupport apparatus 38 is located in the treatment room 15. When thepatient support apparatus 38 is moving between the waiting and treatmentstates, the respective door 19 is open to allow the patient supportapparatus 38 to pass through the respective doorway 17. When the patientsupport apparatus 38 is in its waiting state, the respective door 19 isclosed to isolate the respective waiting room 14 from the treatment room15. In the illustrated embodiment, when the patient support apparatus 38is in its treatment state, the respective door 19 is open to allow theactuation apparatus 40 to extend through the doorway 17. In alternativeembodiments, for example where the base of the actuation apparatus 40 islocated in the treatment room 15, the door 19 may be closed when thepatient support apparatus 38 is in the treatment room 15.

The actuation apparatus 40 is configured to move the respective patientsupport apparatus 38 along at least one axis into and out of thetreatment room 15. In preferred embodiments, the actuation apparatus 40is configured to move the respective patient support apparatus 38 alonga radial axis, i.e. in a direction that is along a radius of thetreatment room 15. The axis is typically a horizontal axis. Optionally,the actuation apparatus 40 is configured to move the respective patientsupport apparatus 38 along one or more other axis, in particular two orthree orthogonal axes, including horizontal and/or vertical axes, asdesired. For example, in addition to the main axial movement into andout of the treatment room 15, the actuation apparatus 40 may beconfigured to move the patient support apparatus 38 up and down and/orfrom side to side (with respect to the main axial direction).

In preferred embodiments, the actuation apparatus 40 is configured torotate, or pivot, the respective patient support apparatus 38 about atleast one axis, including horizontal and/or vertical axes, and/or abouttwo or three orthogonal axes.

In preferred embodiments therefore, the actuation apparatus 40 isconfigured to effect linear movement of the patient support apparatus 38along at least one axis (for movement into and out of the treatment room15) and optionally along two or more orthogonal axes, and optionallyrotational movement of the patient support apparatus 38 about at leastone axis, and optionally about two or more orthogonal axes.

The actuation apparatus 40 may be configured in any conventional mannerin order to achieve the desired movability of the patient supportapparatus 38. By way of example, in the illustrated embodiment theactuation apparatus 40 comprises an articulated arm 44. In this examplethe arm 44 comprises three arm sections 44A, 44B, 44C pivotably coupledto each other in series, each section being coupled to the, or each,adjacent section for pivoting movement about a respective, in use,vertical axis. In alternative embodiments, the arm 44 may have more orfewer arm sections. The first arm section 44A is pivotably coupled to abase 46 for pivoting movement about a respective, in use, vertical axis.The base 46 is located in the respective waiting room 14 in thisexample, although it may alternatively be located elsewhere, e.g. in thetreatment room 15. The coupling between the first arm section 44A andthe base 46 may be configured to raise and lower the arm 44.

The last arm section 44C is coupled to the patient support apparatus 38.In this example the coupling between the arm 44 and the patient supportapparatus 38 allows rotational movement of the patient support apparatus38 about an, in use, vertical axis (or an axis that is perpendicular tothe arm 44). In alternative embodiments, the coupling 48 between the arm44 and the patient support apparatus 38, which may take any convenientconventional form, may be configured to allow additional or alternativemovement of the patient support apparatus 38 with respect to the arm 44.In particular, any of the aforementioned rotational movement may beeffected by the coupling 48 and/or linear movement in a verticaldirection. In cases where the patient support apparatus 38 has more thanone configuration, the coupling 48 may provide all or part of the meansfor operating the patient support apparatus 38 between its respectiveconfigurations.

Typically, the actuation apparatus 40 is power operated, e.g. by one ormore power operated actuators (not shown), which may for example beelectrically or hydraulically operated as is convenient, and may belinear or rotary as required.

In the drawings, the patient support apparatus 38 and associatedactuation apparatus 40 are only shown in one of the waiting rooms 14although it will be understood that each of the waiting rooms 14 isequipped in the same or similar manner. Hence, the system 10 canaccommodate multiple patients at once, one per room 14.

It will be apparent from the foregoing that, in either of the waiting ortreatment states, the patient support apparatus 38 may adopt any one ofa plurality of different positions and/or orientations. However, in thewaiting state (not illustrated) the patient support apparatus 38 islocated in the respective waiting room 14, while in the treatment stateit is located in the treatment room 15.

When in its treatment state, each patient support apparatus 38 occupiesa respective different part of the treatment room 15, typically a partthat is adjacent the respective doorway 17 of the respective waitingroom 14, or which otherwise corresponds with the respective waiting room14, typically in the vicinity of the wall 47. These respective parts ofthe treatment room 15 are spaced apart, usually around or along the wall47 or otherwise around or along the periphery of the treatment room 15.For example in the illustrated embodiment, these respective parts of thetreatment room 15 are radially spaced apart.

Accordingly, in order to treat patients from each waiting room 14, atleast part of the beam delivery system 12 is movable so that it maydeliver a radiation beam to any one of these parts of the treatment room15. In preferred embodiments, the positioning apparatus 18 is operableto move the particle accelerator 16 within the treatment room 15 so thatit may deliver the radiation beam to any one of said parts of thetreatment room 15. Typically this involves moving the particleaccelerator 16 to the respective part of the treatment room 15.

In preferred embodiments, the positioning apparatus 18 is configured tomove the particle accelerator 16 to any one of the treatment parts ofthe treatment room 15, each treatment part being associated with arespective one of the waiting rooms 14. The preferred positioningapparatus 18 comprises a counterbalanced lever 50 that carries theparticle accelerator 16 on one side of a pivot or fulcrum 52, and acounterbalancing unit 54 on the other side of the fulcrum 52. Thefulcrum 52 in this case allows the lever 50 to pivot about an, in use,horizontal axis. The counterbalancing unit 54 may take any suitableform, e.g. comprising any object(s) having a mass that counterbalancesthe particle accelerator 16. Optionally, the counterbalancing unit 54may comprise a second particle accelerator, which may be the same as orsimilar to the particle accelerator 16. This allows a second patient(not shown) from a second waiting room 14 to be treated simultaneouslywith the first patient 26 but in different, typically opposite, parts ofthe treatment room 15.

In the illustrated embodiment, the lever 50 comprises an arm but mayalternatively comprise any other structure that is capable of carryingthe particle accelerator 16 and counterbalancing unit 54. The lever 50is typically of fixed length between the pivot point 52 and the particleaccelerator 16, but may alternatively be extendible in length. The lever50 may be of fixed length between the pivot point 52 and thecounterbalancing unit 54, but may alternatively be extendible in length.In preferred embodiments, the fulcrum 52 is located at the centre of thetreatment room 15 and the length of the lever 50 between the fulcrum 52and the particle accelerator 16 is such that the particle accelerator 16is locatable at any one of the treatment parts of the treatment room 15.

In preferred embodiments, the lever 50 is rotatable about a verticalaxis, i.e. in the floor-to-ceiling direction of the treatment room 15,at the fulcrum 52. Hence, the particle accelerator 16 can be moved fromone treatment part of the treatment room 15 to another treatment part byrotating the lever 50 about the vertical axis. Typically this involvesrotating the lever 50 to align the particle accelerator 16 with anyselected one of the waiting rooms 14, usually with the respectivedoorway 17 of the selected waiting room 14. The arrangement is such thatwhen the patient support apparatus 38 of the respective waiting room 14is in its treatment state, the particle accelerator 16 is in a positionto deliver the radiation beam to the patient 26. Any conventionalsupport mechanism(s) may be used at the fulcrum 52 to enable the desiredpivoting and rotational movement of the lever 50.

Accordingly, in preferred embodiments, the positioning apparatus 18 isable to raise and lower the particle accelerator 16 (in this case bypivoting the lever 50 about a horizontal axis at the fulcrum 52), andmove the particle accelerator 16 from one part of the treatment room 15to another (in this case by rotating the lever 50 about the verticalaxis at the fulcrum 52), advantageously with the assistance of thecounterbalancing provided by the counterbalancing unit 54.

In the drawings, the nozzle 24 is shown in a location from where it candeliver the radiation beam to the patient from beneath the patientsupport apparatus 38. It will be understood that this is exemplary andthat the beam delivery system may alternatively be configured such thatthe nozzle 24 targets the patient from above, or from either side, fromthe front or the rear of the patient support apparatus 38.

In alternative embodiments, the particle accelerator 16 may be carriedby an arm, or other structure, that is capable of being rotated about avertical axis as described above but which is not part of acounterbalanced lever. Such an arrangement allows the particleaccelerator 16 to be moved from one treatment part of the treatment room15 to another, but the lack of a counterbalance makes the particleaccelerator 16 difficult to manoeuvre.

In preferred embodiments, the particle accelerator 16 is carried by ahead unit 60 of the positioning apparatus 18, which is convenientlyprovided at the free end of the lever 50. Advantageously the particleaccelerator 16 is rotatable with respect to the head unit 60 about anaxis that is perpendicular to the longitudinal axis of the lever 50. Thehead unit 60 may be rotatable with respect to the lever 50 about an axisthat is parallel with the longitudinal axis of the lever 50. Moregenerally, the particle accelerator 16 may be coupled to the positioningapparatus 18 for rotational movement about at least one axis, or two orthree orthogonal axes, with respect to a supporting structure such asthe arm 56 or lever 50.

In alternative embodiments (not illustrated) the nozzle 24 may beconnected to the particle accelerator 16 by a beam transport systemconfigured to allow the radiation beam to be delivered to any one ofsaid parts of the treatment room 15. For example the beam transportsystem may provide a respective beam transport path to each part of thetreatment room 15, or may support movement of the nozzle 24 from onelocation to another. The beam transport system may be conventional indesign, typically including one or more vacuum tubes, and components(e.g. magnets) for beam bending, beam focusing and/or energy selection).

Optionally, the positioning apparatus 18, or more generally the beamdelivery system 12, is mounted on a platform (not shown) or otherlifting structure that is movable in a vertical direction, i.e. in thefloor-to-ceiling direction of the treatment room 15, in order to raiseand lower the positioning apparatus 18/beam delivery system 12. This isparticularly useful in cases where the beam delivery system 12 isrequired to service waiting rooms 14 arranged in more than one tier.

Preferably, the positioning apparatus 18 is power operated, e.g. by oneor more power operated actuators (now shown), which may for example beelectrically or hydraulically operated as is convenient, and may belinear or rotary as required.

During use, the positioning apparatus 18 moves the particle accelerator16 to any one of a plurality of treatment locations within the treatmentroom 15, each treatment location being a respective part of thetreatment room 15 that is associated with a respective one of thewaiting rooms 14. In preferred embodiments, this is achieved by rotatingthe positioning apparatus 18, and more particularly lever 50, about avertical axis to locate the particle accelerator 16 in any one of thetreatment locations as determined by the rotational position of thelever 50. When the particle accelerator 16 is at the treatment locationfor a given waiting room 14 (the treatment location typically beingadjacent the doorway 17 of the respective room 14), and the patientsupport apparatus 38 of the respective room 14 is in its treatmentstate, the beam delivery system 12 can be operated to deliver theradiation beam to the patient 26 on the support apparatus 38. Aftertreatment is completed, the positioning apparatus 18 may move theparticle accelerator 16 to another one of the treatment locations inorder to treat a patient from another of the waiting rooms 14.Accordingly, the particle accelerator 16 is moved within the treatmentroom 15 from one treatment location to another in order to treatpatients from any one or more of the waiting rooms 14, one patient at atime. Hence the beam delivery system 12 is shared by multiple waitingrooms 14. For example, the therapy system 10 may be operated to delivera radiation beam to treatment locations associated with two or more ofthe waiting rooms 14 in succession, conveniently in a progressiveangular direction around the ring of rooms 14, in order to treat arespective patient 26 from each room.

Preferably, the door 19 of each waiting room 14 that is not at any giventime being serviced by the beam delivery system 12, is closed.

Systems 10 embodying the invention typically include a control system(not shown), which may be located in a separate room. The control systemmay include equipment for controlling and monitoring any aspect of thesystem 10 and may take any suitable conventional form, typicallyincluding suitable programmed computing device(s). The control systemtypically includes means for controlling and/or monitoring the operationof any one or more of the accelerator 16 (including the nozzle 24),positioning apparatus 18, the actuation apparatus 40, the patientsupport apparatus 38 and the doors 19 as applicable. The control systemmay include components (e.g. scanner(s), visual display unit(s) and userinterface device(s)) of an imaging system for controlling and/ormonitoring operation of the system 10. The imaging system may compriseany one or more of an MRI system, PET system, SPECT system or CT system.The control system may be configured to control any one or morecomponents of the system 10 collectively or individually.

Preferred embodiments of the invention provide a low redundancy,centralised, therapy system with highly configurable (i.e. can be placedat any position in space and be rotated in all planes i.e. 6D(x,y,z,θ,ϕ) radiation delivery.

Preferred embodiments include a centralised beam delivery system 12,which may produce radiation from single or multiple radiation sources(to provide redundancy for maintenance, which is optional), that can bearbitrarily positioned in up to three dimensions and pointed in anydirection such that the emitted radiation beam can be targeted on apatient from any one of a plurality of waiting rooms at a range ofangles.

Each waiting room 14 advantageously has a patient support apparatus 38that can be positioned in up to 6 cartesian dimensions (x,y,z,θ,ϕ,Ψ),optionally with additional reclining adjustments, and optionally withdifferent support heights, and/or different positions and angles withrespect to the room. The preferred patient support apparatus 38 isadjustable to move the patient along one axis, or in two or threeorthogonal axial directions (a vertical axis and two perpendicularhorizontal axes).

Advantageously, the patient support apparatus is adjustable to pivot thepatient about at least one, or two or three orthogonal axes (a verticalaxis and two perpendicular horizontal axes). This facilitates a widerange of relative angles and positions of the delivered radiation beamrelative to the patient support apparatus.

Advantageously, the adjustability of the patient support apparatus 38(as facilitated at least in part by the actuation apparatus 40) and/orof the beam delivery system 12 (as facilitated by the positioningapparatus 18 and the accelerator 16) individually or together allow theradiation beam to be delivered in a precise and highly adjustable manner(advantageously in up to 6 cartesian dimensions (x,y,z,θ,ϕ,Ψ)) to atarget zone in any one of the treatment locations of the treatment room15. In particular the radiation beam may be targeted at the target zone3 dimensionally.

Advantageously, the adjustability of the beam delivery system 12 isconfigured to provide isocentric delivery of the radiation beam to atarget zone in any one of the treatment locations in the treatment room15 (which target zone coincides in use with a patient on the relevantpatient support apparatus 38). Advantageously, the system 10 allowssubstantially full 3-D Isocentric irradiation of a patient, suitable forintensity modulated therapy or spot scanning.

Scanning of the radiation beam about at least one and preferably twoperpendicular axes (e.g. a vertical axis and a perpendicular horizontalaxis running transversely of the room) may be supported, conveniently byincorporation of scanning magnets in the nozzle 24.

Advantageously, during use the relative positions and angles of thesystem 10 may be adjusted to achieve isocentric irradiation of thetarget zone.

The use of a counterbalanced positioning apparatus is advantageous inthat it allows the particle accelerator 16 to be moved in the mannerdescribed, which would be beyond the capability of conventional robotssince particle accelerators can weight between 100-200 tonnes and so areconventionally deployed statically.

Providing the nozzle 24 at the particle accelerator 16 without anintermediate beam transport system is advantageous since it avoids orreduces beam degradation and collateral residual radiation that can becaused by bending magnets and other components of a beam transportsystem. Moreover, as there is no long beam line or 2D gantry, themaintenance, energy requirements, size, scale and costs of the systemare reduced in comparison with conventional systems.

During use, the control system obtains treatment information in respectof the next waiting room 14 to be serviced. The treatment informationtypically includes beam delivery vector(s) for targeting the beam on atarget zone, and dosage information. The control system then causes thepositioning apparatus 18 to position the particle accelerator 16 at therelevant treatment location in the room 15, as well as positioning thenozzle 24 in a desired position and/or orientation as determined fromthe treatment information, i.e. in order to deliver the radiation beamat the required delivery vector(s).

3D targeting of the radiation beam may be performed by a laser so thatthe radiation beam always impinges on the target zone as desired.

In preferred embodiments, the control system includes one or moredevices (e.g. cameras and/or motion sensors and/or pressure sensors) fordetecting movement of the patient when on the patient support apparatus38. The control system may be configured to use any detected movement ofthe patient to re-position one or more component of the system 10, inparticular of the beam delivery system 12, to ensure that the radiationbeam is correctly targeted on the patient, i.e. the delivery of the beamautomatically tracks any detected movement of the patient during use.Optionally, if any detected movement exceeds a threshold level, then thecontrol system may be configured to cease treatment.

The invention is not limited to the embodiment(s) described herein butcan be amended or modified without departing from the scope of thepresent invention.

1. A radiation therapy system comprising: a beam delivery system locatedin a treatment room, the beam delivery system comprising a particleaccelerator for generating a radiation beam, and a positioning apparatusfor moving said particle accelerator to any one of a plurality oftreatment locations in said treatment room; a plurality of waitingrooms; a respective doorway between each waiting room and said treatmentroom; a respective patient support apparatus for each waiting room; anda respective actuation apparatus for moving each patient supportapparatus between a waiting state in which it is located in therespective waiting room, and a treatment state in which it is located ina respective one of said treatment locations in said treatment room. 2.The system of claim 1, wherein said positioning apparatus comprises acounterbalanced lever carrying the particle accelerator.
 3. The systemof claim 2, wherein said lever is pivotable at a fulcrum about ahorizontal axis, said fulcrum preferably being located at the centre ofsaid treatment room.
 4. The system of claim 3, wherein said particleaccelerator is located on one side of said fulcrum and acounterbalancing unit is provided on the other side of the fulcrum. 5.The system of any claim 1, wherein said positioning apparatus isrotatable about a vertical axis to move said particle accelerator to anyone of said treatment locations, said vertical axis preferably beinglocated at the centre of said treatment room.
 6. (canceled)
 7. Thesystem of claim 1, wherein the particle accelerator is coupled to thepositioning apparatus for rotational movement about at least one axis,or two or three orthogonal axes, with respect to the positioningapparatus.
 8. The system of claim 1, wherein said particle acceleratoris provided with a beam output device, preferably comprising a beamdelivery nozzle, and wherein there is no beam transport system betweenthe particle accelerator and the beam output device
 9. The system ofclaim 8, wherein the beam output device is fixed with respect to theparticle accelerator so that it moves with the particle accelerator. 10.(canceled)
 11. (canceled)
 12. The system of claim 1, wherein each ofsaid treatment locations is a respective part of said treatment roomassociated with a respective one of said waiting rooms, being adjacent adoor of a respective one of said waiting rooms.
 13. (canceled)
 14. Thesystem of claim 1, wherein at least some of, and preferably all of, saidwaiting rooms are radially spaced apart around said treatment room, saidwaiting rooms being arranged in a ring around said treatment room. 15.(canceled)
 16. The system of claim 1, wherein said actuation apparatusis configured to move the respective patient support apparatus in a mainaxial direction into and out of the treatment room, said main axialdirection preferably being radially disposed with respect to saidtreatment room, said actuation apparatus being configured to move therespective patient support apparatus along two or three orthogonal axesand/or to effect rotational movement of the patient support apparatusabout at least one axis, and optionally about two or three orthogonalaxes.
 17. (canceled)
 18. (canceled)
 19. The system of claim 1, whereinsaid actuation apparatus comprises an articulated arm coupled between abase and said patient support apparatus.
 20. (canceled)
 21. The systemof claim 19, wherein said base is located in the respective waitingroom.
 22. The system of claim 1, wherein said actuation apparatus and/orsaid positioning apparatus are power operated.
 23. The system of claim1, further including a control system for controlling said beam deliverysystem for delivering a radiation beam to a target zone in accordancewith a three dimensional beam delivery vector, and wherein said controlsystem is configured to control any one or more of: the rotationalposition of the positioning apparatus about a vertical axis; the heightof the particle accelerator; the rotational position of the particleaccelerator about one or more axis.
 24. The system of claim 1, whereinsaid control system is configured to control said beam delivery systemby operating said positioning apparatus to position said particleaccelerator for delivering said radiation beam to said target zone inaccordance with said three dimensional beam delivery vector. 25.(canceled)
 26. The system of claim 1, further including means fordetecting movement of a patient on the patient support apparatus, thesystem being responsive to detected patient movement to adjust theposition of said particle accelerator, and/or being responsive todetected patient movement of more than a threshold amount to stopdelivery of said radiation beam.
 27. The system of claim 23, whereinsaid control system is responsive to detected patient movement to adjustsaid beam delivery system for maintaining delivery of said radiationbeam to said target zone in accordance with said three dimensional beamdelivery vector.
 28. (canceled)
 29. The system of claim 1, wherein saidparticle accelerator is a proton accelerator and said radiation beam isa proton beam.
 30. A beam delivery system for a radiotherapy system, thebeam delivery system comprising a particle accelerator for generating aradiation beam and a positioning apparatus for moving said particleaccelerator, wherein said positioning apparatus comprises acounterbalanced lever carrying the particle accelerator.